Costa is one of the most expensive Premier League imports of this transfer window but with that hefty price tag comes a certain level of expectation. Costa may not have lit up the World Cup quite as he had hoped as his Spain side crashed out early, but the Brazil-born striker has already shown what he is capable of in a series of pre-season performances that will have Chelsea fans salivating at the prospect of watching him this season - and opposition defenders quaking in their boots.

The king of west London has returned and those who aren't getting excited by the prospect of watching Drogba run out at Stamford Bridge in a Chelsea shirt once more need their pulses checking. Love him (Chelsea fans) or hate him (everyone else), it's nevertheless impossible to take your eye off the Ivorian and it will be fascinating to see how he re-adapts to life in England after his stint in Turkey and whether his reunion with Jose Mourinho can inspire glimpses of his former Chelsea glories. It's just a shame he looks like starting the season as third-choice striker, behind Costa and Fernando Torres.

United have been searching for a player of Herrera's ilk for years - ever since Paul Scholes began to wane - and after last summer's failed pursuit, they now finally have their man. The young Spaniard rose to prominence when his Athletic Bilbao side dismantled Alex Ferguson's team in the Europa League during the 2011-12 season, and if he can recreate that level of play to his new team - pre-season form largely indicates that is an entirely likely scenario - Herrera could well prove to be a key factor in any rebirth of the fallen giants under the new stewardship of Louis van Gaal. United fans have good reason to be excited.

Earlier this summer, the headlines read: 'Barcelona star signs for Stoke'. Who'd have thought that would ever happen? But it has, and Bojan will showcase his talents at the Britannia Stadium instead of the Nou Camp this season. A player who counts Barca, Roma, AC Milan and Ajax as his former clubs cannot fail to bring a big-club mentality with him and while he has largely failed to live up to the early promise he showed when he first burst onto the scene in 2007, at just 23 years of age, Bojan still has time on his side and the potential to light up the Potteries.

Mauro Zarate (Velez Sarsfield to West Ham, undisclosed)

Zarate returns to these shores having already given the Premier League a glimpse of his capabilities during a brief loan spell with Birmingham in 2008. His goals then, albeit few and far between, got the juices flowing and despite his subsequent time in Italy trailing off slightly after a move from Lazio to Internazionale, a season back at his first club Velez Sarsfeld has apparently reinvigorated his career. Zarate arrives as the Argentine league's top scorer last season, and Hammers fans can look forward to Zarate attempting to emulate a previous Argentine success story at Upton Park: Carlos Tevez.

Lampard wearing anything other than a Chelsea strip was always going to look a bit odd, considering his 13 years of service for the Stamford Bridge club. But few were expecting his new shirt to be a Manchester City one. Yet the surprise loan deal from New York City FC only adds to the interest in seeing how Lampard will fare having finally left the club where he made his name. He may not be the player he was in his Chelsea prime, but there is no doubting he can still do a job at City - and maybe even add to his incredible scoring record.

With the benefit of hindsight, it's easy to see that Jack Rodwell's move from Everton to Manchester City was a poor decision from all parties involved. A promising young player, a real England prospect, saw his hopes of playing regularly severely restricted as he fell victim to City's policy of bloating their squad to the point of bursting. Yet Rodwell hasn't become a bad player, and at Sunderland he should finally be able to flourish, perhaps even fulfil the potential he displayed during his time at Goodison. His journey from here will be exciting to watch.

There is little not to like about the England midfielder's game and, having excelled last season with Southampton, Lallana could further flourish under Brendan Rodgers at Liverpool. His style is well suited to how Rodgers likes to encourage his side to play - and vice versa - meaning Lallana has the potential to become one of this season's standout performers. And what's not exciting about the prospect of that?

Finally the England goalkeeper will have the chance to prove his worth in the Premier League, having spent the vast majority of his professional career with Celtic in the SPL/Scottish Premiership, a league that will not have tested him like the English top flight will. While he may not be the most exciting player to watch - he's a keeper, after all - the progress he makes at Southampton, and more to the point in the Premier League, will be fascinating to follow.

Sanchez's arrival at the Emirates continues Arsenal's recently-discovered ability to dig deep to bring in big names, the previous tight-fisted mould having been broken by the signing of Mesut Ozil last summer. And, like Ozil, much is expected of Sanchez, partly due to the necessity of paying back that transfer fee with performances on the pitch, but also because of his pedigree. The Chilean is a genuine world class player, no doubt - his performances for Chile in Brazil only added to that argument - and already Arsenal have sent out a message to their rivals this season with victory in the Community Shield. With Sanchez in their line-up, there is talk of this being the most exciting Arsenal side seen for years.

That's not all though - honourable mentions should also go to the likes of Lazar Markovic (Benfica to Liverpool, £20m), Muhamed Besic (Ferencvaros to Everton, £4m), Emmanuel Riviere (Monaco to Newcastle, £6.3m), Bafétimbi Gomis (Lyon to Swansea), Siem de Jong (Ajax to Newcastle, £6m) and Enner Valencia (Pachuca to West Ham, £12m).